在我们工作中，常常会碰到树形组件的生成问题，如果你在开发web application,纯粹使用
javascript来生成树形组件是非常繁琐的，而且交互性也不不太好。所以许多产品使applet来实现树形组件的功能。比如说，weblogic,jboss等产品的console.所以，把树形数据组织成xml文件，用jdom剖析它，最后生成applet就非常有通用的意义。下面，我就给出一个例子，抛砖引玉。
1.准备一个存有属性数据的xml文件，把它放在classpath中，我这里是org.xml。
<?xml version="1.0" encoding="UTF-8"?><!--Sample XML file generated by XMLSPY v5 rel. 3 U (http://www.xmlspy.com)--><node xmlns="http://www.javabox.com/schemas/org" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.javabox.com/schemas/orgE:myDemoorg.xsd" name="组织机构" id="-1" desc="" link="#"> <node name="总经理" id="1" desc="" link="#"> <node name="管理副总经理" id="2" desc="" link="#"/> <node name="生产副总经理" id="3" desc="" link="#"> <node name="项目部" id="7" desc="" link="#"/> <node name="机械公司" id="8" desc="" link="#"/> <node name="贝盟公司" id="9" desc="" link="#"/> <node name="洛斯韦公司" id="9" desc="" link="#"/> </node> <node name="总工程师" id="4" desc="" link="#"/> <node name="总会计师" id="5" desc="" link="#"/> <node name="总经济师" id="6" desc="" link="#"/> </node></node>
2.确保你可以使用jdom解析器，你如果没有可以去这里下载。
3.用于代表树结点节点的javabean,TreeNode.java
package com.javabox.jtree;public class TreeNode{ private String id; private String name; private String link; public TreeNode(String id,String name,String link){ this.id=id; this.name=name; this.link=link; } public String getId(){ return id; } public void setId(String Id){ this.id=Id; } public void setName(String Name){ this.name=Name; } public String getName(){ return name; } public String toString(){ return name; } public String getLink(){ return link; } public void setLink(String link){ this.link=link; }}
4.自己写的TreeCellRenderer,IconRender.java
package com.javabox.jtree;import javax.swing.*;import java.awt.*;import javax.swing.tree.*;import javax.swing.tree.DefaultTreeCellRenderer;class IconRender extends DefaultTreeCellRenderer { //你需要替换成你的icon public static final Icon leafSelectedIcon = new ImageIcon("greeball.JPG"); public static final Icon leafUnSelectedIcon = new ImageIcon("greyball.JPG"); public static final Icon folderOpen = new ImageIcon("folderopen.JPG"); public static final Icon folderClose = new ImageIcon("folderclose.JPG"); public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) { super.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus); if (leaf && selected) { setIcon(IconRender.leafSelectedIcon); } else if (leaf) { setIcon(IconRender.leafUnSelectedIcon); } return this; } public IconRender() { super(); this.setLeafIcon(leafUnSelectedIcon); this.setOpenIcon(folderOpen); this.setClosedIcon(folderClose); }}
5.AppletTree.java,该文件解析xml文件，生成含Jtree的applet，你可以把它嵌入到jsp,html文件中使用，也可以直接运行该文件。
package com.javabox.jtree;import javax.swing.event.*;import java.awt.*;import java.applet.*;import javax.swing.*;import javax.swing.tree.*;import java.awt.event.*;import org.jdom.*;import org.jdom.input.*;import java.io.*;import java.util.*;import java.awt.*;import javax.swing.*;import javax.swing.border.*;import javax.swing.plaf.*;import javax.swing.plaf.basic.*;import javax.swing.plaf.metal.*;import java.io.*;import netscape.javascript.*;public class AppletTree extends Applet implements TreeSelectionListener{ private JTree tree; private TreePath path; private Panel topPanel; private DefaultMutableTreeNode top; private DefaultMutableTreeNode clicknode; private String link; public AppletTree(){ } public void init(){ try{ super.init(); this.setLayout(new GridLayout(1,1)); tree=createTree(new FileInputStream("org.xml")); tree.getSelectionModel().setSelectionMode(TreeSelectionModel.SINGLE_TREE_SELECTION); tree.putClientProperty("JTree.lineStyle","Angled"); tree.setShowsRootHandles(true); tree.setEditable(false); tree.addTreeSelectionListener( this ); IconRender render=new IconRender(); tree.setCellRenderer(render); topPanel=new Panel(new BorderLayout()); topPanel.add(tree); this.add(topPanel); }catch(Exception e){ e.printStackTrace(); } } public JTree createTree(InputStream is){ SAXBuilder builder = new SAXBuilder(); try { Document doc = builder.build(is); Element root=doc.getRootElement(); TreeNode rootNode=new TreeNode(root.getAttributeValue("id"),root.getAttributeValue("name"),root.getAttributeValue("link")); top=new DefaultMutableTreeNode(rootNode); addNode(root,top); } catch (Exception ex) { ex.printStackTrace(); } //你可以在这里改变jtree中连线的颜色，我请教国外的高手才找到的，很酷的哦:) UIManager.put( "Tree.hash", new ColorUIResource(Color.red) ); return new JTree(top); } /** * * @param e 待加入树种的jdom元素 * @param rootNode 树根节点 */ private void addNode(Element e,DefaultMutableTreeNode rootNode){ String id=e.getAttributeValue("id"); String name=e.getAttributeValue("name"); String link=e.getAttributeValue("link"); TreeNode node=new TreeNode(id,name,link); //如有父节点 Element father=e.getParent(); if(father!=null){ String fid=father.getAttributeValue("id"); DefaultMutableTreeNode fatherNode=getTreeNode(fid,rootNode); if(fatherNode!=null){ fatherNode.add(new DefaultMutableTreeNode(node)); } } //如有子节点 Iterator it=e.getChildren().iterator(); while(it.hasNext()){ Element child=(Element)it.next(); addNode(child,rootNode); } } /** * 根据id,查找树节点,//广度优先 * @param id 节点id * @param rootNode 树根节点 * @return DefaultMutableTreeNode */ private DefaultMutableTreeNode getTreeNode(String id,DefaultMutableTreeNode rootNode){ DefaultMutableTreeNode returnNode=null; if(rootNode!=null){ Enumeration enum=rootNode.breadthFirstEnumeration(); while(enum.hasMoreElements()){ DefaultMutableTreeNode temp=(DefaultMutableTreeNode)enum.nextElement(); TreeNode node=(TreeNode)temp.getUserObject(); if(node.getId().equals(id)){ returnNode=temp; break; } } } return returnNode; } public void valueChanged( TreeSelectionEvent event ){ if( event.getSource() == tree ){ path = event.getPath(); clicknode=(DefaultMutableTreeNode)path.getLastPathComponent(); Object uo=clicknode.getUserObject(); if(uo instanceof TreeNode){ TreeNode nd=(TreeNode)clicknode.getUserObject(); link=nd.getLink(); } //调用一个javascript函数； // JSObject.getWindow (this).eval ("javascript:window.open(´"+link+"´)") ; } } public static void main(String[] args ){ JFrame frame=new JFrame("test"); AppletTree tree=new AppletTree(); tree.init(); frame.getContentPane().add(tree); frame.setSize(600,600); frame.show(); }}
6.运行一个这个类，是不是很cool哦，你还可以把它嵌在网页中，调用javasript函数，达到刷新页面的目的。
希望该文章能对你有所启发，祝你成功！
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